A nonaqueous electrolyte secondary battery using a titanium compound for a negative electrode active material is used in a field where a stable battery excellent in safety, long life and rate characteristic is required. On the other hand, increasing an output of a nonaqueous electrolyte secondary battery is also required from the market.
For example, there is a method for increasing a battery output by reducing a particle diameter of a negative electrode active material to widen a specific surface area. However, when the particle diameter of the active material is reduced, a binding property with a base material of an electrode weakens. As a result, there is a problem that the active material falls off and the battery causes a micro short circuit.
As a countermeasure, Patent Document 1 describes a technique for improving a binding force between a negative electrode base material and a negative electrode active material by using a PVdF having a carboxyl group as a negative electrode binder.